I have a folder, that has index.js and a couple of models (classes)
index.js
module.exports = {
Book : require('./book'),
Author : require('./author')
}
book.js
var Author = require('./author')
var Book = models.ActiveRecord.extend({
schema : {
belongsTo : {
author : Author
}
}
})
module.exports = Book
author.js
var Book = require('./book')
var Author = models.ActiveRecord.extend({
schema : {
hasMany : {
author : Book
}
}
})
module.exports = Author
The problem is that Author class does not seem to find the Book! It's just an empty Object.
However, if I switch the exports in index.js, putting Book after Author - it works, but then the other model stops working.
I don't want to do any hacks to make it work.
This is because you have a circular dependency. Node.js handles this in a very specific way:
The first module loads and runs (in this case, book.js). It (book.js) will load and run the second module (author.js) when it (book.js) requires the other (author.js)
When the second module (author.js) is loaded and run, it (author.js) requires the first module (book.js) but it (author.js) will receive a partially filled object - however many things were set on the exports in book.js before it required author.js will be in that object
After book.js is completely run through, the object author.js got from require('./book') will be the full book.js module object
For more info, here's the docs: http://nodejs.org/api/modules.html
If its possible to dynamically add that schema to one of those ActiveRecord objects, that's one way to solve this. This is actually kind of a tricky situation. In fact, even without the module system, this would cause problems for you. If you put all this code in one file, how would you make it work?
Related
I have a configuration application in Nodejs. It has a Component with name and uuid. A Component can have many Schemas. A Schema has a uuid, name, componentId, json. A Schema can have many Configurations. A Configuration has name, schemaId, json and uuid. A Schema can contain reference of many other Schemas in it. Now I want to create a functionality of exporting all the data from one instance of the application and import it in another. What should be the simplest way to do it? a few questions are
How to tell application what to export. for now i think there should be separate arrays for components, schemas and configurations. Like
{
components: ['id1', 'id2'],
schemas: ['s1', 's2'],
configuration: ['c1', 'c2'],
}
this data should be sent to application to return a file with all information that will later be used for importing in another instance
The real question is how should my export file look like keeping in mind that dependencies are also involved and dependencies can also overlap. for example a schema can have many other schemas referenced in its json field. eg schema1 has schema2 and schema4 as its dependencies. so there is another schema schema5 that also require schema2. so while importing we have to make sure that schema2 should be saved first before saving schema1 and schema5. how to represent such file that requires order as well as overlapped dependencies, making sure that schema2 is not saved twice while importing. json of schema1 is shown below as an example
{
"$schema": "http://json-schema.org/draft-04/schema#",
"p1": {
"$ref": "link-to-schema2"
},
"p2": {
"$ref": "link-to-schema4"
},
}
What should be the step wise sudo algorithm i should follow while importing.
This is a perfect occasion for a topological sort.
Taking away components, schemas and configurations terminology, what you have is objects (of various kinds) which depend on other objects existing first. A topological sort will create an order that has only forward dependencies (assuming you don't have circular ones, in which case it is impossible).
But the complication is that you have dependency information in a mix of directions. A component has to be created before its schema. A schema has to be created after the schemas that it depends on. It is not impossible that those schemas may belong to other components that have to be created as well.
The first step is to write a function that takes an object and returns a set of dependency relationships discoverable from the object itself. So we want dependencyRelations(object1 to give something like [[object1, object2], [object3, object1], [object1, object4]]. Where object1 depends on object2 existing. (Note, object1 will be in each pair but can be first or second.)
If every object has a method named uniqueName that uniquely identifies it then we can write a method that works something like this (apologies, all code was typed here and not tested, there are probably syntax errors but the idea is right):
function dependencyInfo (startingObject) {
const nameToObject = {};
const dependencyOf = {};
const todo = [startingObject];
const visited = {};
while (0 < todo.length) {
let obj = todo.pop();
let objName = obj.uniqueName();
if (! visited[ objName ]) {
visited[ objName ] = true;
nameToObject[objName] = obj;
dependencyRelations(obj).forEach((pair) => {
const [from, to] = pair;
// It is OK to put things in todo that are visited, we just don't process again.
todo.push(from);
todo.push(to);
if (! dependencyOf[from.uniqueName()]) {
dependencyOf[from.uniqueName()] = {}
}
dependencyOf[from.uniqueName()] = to.uniqueName();
});
}
}
return [nameToObject, dependencyOf];
}
This function will construct the dependency graph. But we still need to do a topological sort to get dependencies first.
function objectsInOrder (nameToObject, dependencyOf) {
const answer = [];
visited = {};
// Trick for a recursive function local to my environment.
let addObject = undefined;
addObject = function (objName) {
if (! visited[objName]) {
visited[objName] = true; // Only process once.
// Add dependencies
Object.keys(dependencyOf[objName]).forEach(addObject);
answer.push(nameToObject[objName]);
}
};
Object.keys(dependencyOf).forEach(addObject);
return answer;
}
And now we have an array of objects such that each depends on the previous ones only. Send that, and at the other end you just inflate each object in turn.
I'm trying to work with shadow roots in my Testcafe project. It's a little bit complicated to deal with it. I create a custom function that behaves the same as Selector().find() but I struggle with this error :
The "boundTestRun" option value is expected to be a test controller.
when I'm doing as documented here :
import { Selector, t } from 'testcafe'
getInShadowRoot = Selector(
// More code here
)
const boundedGetInShadowRoot = this.getInShadowRoot.with({ boundTestRun: t })
I create a gist to illustrate my problem: https://gist.github.com/HugoDel/a600f3e120674e3f255884f3dc84fee3
Thanks for your help!
Edit:
I finally get rid of it since I don't need to add .with({ boundTestRun: t }) to make it work.
I use mongoose random plugin.
In my schema definition i call
GameSchema.plugin(random, { path: 'r' });
After that I have a custom static method who use the plugin:
GameSchema.statics.someMethod {
[...]
GameSchema.findRandom...
And I get the error
TypeError: Object #<Schema> has no method 'findRandom'
Is there a way to achieve what I am trying to do or should I implement some kind of repository ?
EDIT:
Ben's answer worked, I needed to use findRandom on the model and not the schema.
Precision for those in my case: you need to declare first your static function
GameSchema.statics.someMethod {
[...]
Game.findRandom...
then register your schema
var Game = mongoose.model('Game', GameSchema);
otherwise you'll get "Model .... has no method 'someMethod'"
Game variable in the static function is recognized event though it is defined only later in the script.
=> bonus question: does anyone know why it works ?
You're calling the method on the schema, whereas you need to be calling it on the model.
var Game = mongoose.model('Game', GameSchema);
Game.findRandom()...
I'm trying to create a small EmberJS application, but I'm struggling about how to architecture it correctly. I have a main view called "library" which displays on a sidebar a list of folders. User can click on each folder and display the content at the center (while the sidebar is still active).
I therefore have a library resource, and nested resources to display the folders in this specific context:
this.resource('library', function() {
this.resource('libraryFolders', {path: 'folders'}, function() {
this.resource('libraryFolder', {path: ':folder_id'};
}
};
To be able to access the folders in the parent root, I set up a dependency:
App.LibraryController = Ember.Controller.extend({
needs: ["libraryFolders"],
folders: null,
foldersBinding: "controllers.libraryFolders"
});
App.LibraryRoute = Ember.Route.extend({
setupController: function(controller) {
controller.set('controllers.libraryFolders.model', App.Folder.find());
}
});
First question: is this a good way? I feel it a bit strange that a parent controller have a dependency to its children.
Now, another problem arises: what if I want to reuse folders in another context? All the methods I would write in LibraryFoldersController would be specific to this one, not really DRY. What I came up is adding a root "folders" resource, and add the dependency to this one instead:
this.resources('folders');
App.LibraryController = Ember.Controller.extend({
needs: ["Folders"],
folders: null,
foldersBinding: "controllers.folders"
});
App.LibraryRoute = Ember.Route.extend({
setupController: function(controller) {
controller.set('controllers.folders.model', App.Folder.find());
}
});
What do you think? Am I doing it wrong?
IMO it looks good so far. You are using the needs API which is the correct (ember) way to setup dependencies between controllers.
Maybe if you find yourself writing repeating code you could consider creating a Mixin for a more general controller an put there your logic, that should be agnostic to the use cases it handles.
For example defined a mixin:
App.ControllerMixin = Ember.Mixin.create({
// "use case" agnostic logic here
});
You mix mixins into classes by passing them as the first arguments to .extend.
App.LibraryController = Ember.ObjectController.extend(App.ControllerMixin, {
// now you can use here the logic defined in your mixin
// and add custom code as you please
});
Another possibility is to write a super class and then extend from it to inherit common logic:
Snippet taken from the docs:
App.Person = Ember.Object.extend({
helloWorld: function() {
alert("Hi, my name is " + this.get('name'));
}
});
var tom = App.Person.create({
name: 'Tom Dale'
});
tom.helloWorld(); // alerts "Hi, my name is Tom Dale".
One thing worth mentioning (though I think it's simply a typo) is: needs: ["Folders"] should be needs: ["folders"],
Hope it helps.
After another long research, sth comes out :-) It seems the problem is about the function "getObjectByName". It can not work well with requireJS(ADM). Currently, I have to setup a globel var to fix the problem. I am sure there must be have better solution.
Here is my temp soluton:
(1) setup a global var and setup the search model scope to the global ("APP")
var APP = {};
define(['backbone-relational'], function(){
Backbone.Relational.store.addModelScope(APP);
})
(2) export your relation model to the global
APP.YourRelationalModel = YourRelationModel;
It works, not good though... I'm really looking forward to a better answer. Thanks.
//------------
test versions:
1.Backbone-Relational 0.8.5
2.Backbone 1.0.0 and Underscore 1.4.4
3.JQuery 1.8.3
4.RequireJS 2.1.5
Code is very simple: (or see https://github.com/bighammer/test_relational_amd.git)
require.config({
paths : {
js : 'js',
jquery : 'js/jquery-1.8.3',
underscore : 'js/underscore',
backbone : 'js/backbone',
'backbone-relational' : 'js/backbone-relational'
},
shim : {
underscore : {
exports : '_'
},
backbone : {
deps : ['underscore', 'jquery'],
exports : 'Backbone'
},
'backbone-relational' : {
deps: ['backbone']
}
}
});
define(['backbone', 'backbone-relational'], function (Backbone) {
var Child = Backbone.RelationalModel.extend();
var Parent = Backbone.RelationalModel.extend({
relations : [
{
key : 'child',
type : Backbone.HasOne,
relatedModel : 'Child'
}
]
});
var test = new Parent();
});
save above code in main.js and included in index.html as follows:
It doesn't work. There is warning message:
Relation=child: missing model, key or relatedModel (function (){ return parent.apply(this, arguments); }, "child", undefined).
I read the source code of backbone-relational and know there is something wrong with the namespace. Relational-Backbone cannot find the relatedModel defined in "Parent" (i.e. cannot find releatedMode:"Child"). I failed to find the solution to fix this due to my limited knowledge of javascript :-)
Can anyone help me with this?
Before I asked my question, I studied the following solutions:
Backbone.RelationalModel using requireJs
Can't get Backbone-relational to work with AMD (RequireJS)
Loading Backbone.Relational using Use! plugin
None of them worked in this case.
You don't have to reference relatedModel by string, you can reference it directly, so instead of relatedModel: 'Child', just use: relatedModel: Child.
And since you are using requireJS, you can reference model from other file easily.
define(['backbone', 'models/child', 'backbone-relational'], function (Backbone, Child) {
var Parent = Backbone.RelationalModel.extend({
relations : [{
key : 'child',
type : Backbone.HasOne,
relatedModel : Child
}]
});
var test = new Parent();
});
The above solution didn't apply to me. I am gradually moving code out of Rails Asset Pipeline (not RequireJS/AMD/CommonJS/anything) into Webpack, starting with dependencies. When I moved requiring backbone-relational into Webpack bundle preparation by my models and relation definitions were still in Rails Asset Pipeline, I started getting a lot of unexplained Relation=child: missing model, key or relatedModel (function (){ return parent.apply(this, arguments); }, "child", undefined).
In my case, the solution ended up being quite simple, despite taking a long time to discover on my part:
// In a Webpack module, later included into Rails Asset Pipeline
// temporarily to facilitate migration
require('expose?Backbone!backbone') // Exposing just for migration
require('backbone-relational')
Backbone.Relational.store.addModelScope(window)
backbone-relational by default uses its global scope to resolve string-based relatedModels but since it was required without a real global scope, the solution is simply to pass that in using addModelScope so it can search that scope for the specified models.